Submersible sampler

ABSTRACT

One or more receptacles are mounted on a frame so that they can be released therefrom. The receptacles are evacuated before use and are connected with a thin readily flexible hose which has sealingly received in its free end a glass tube, an exposed end portion of which is sealed so that the vacuum in the receptacles is not broken. The tube is so looped and the glass tube so held, that when the device is actuated the glass tube will be broken so as to permit aspiration of a water sample into the receptacle. A time delay device closes the flexible tube after a predetermined period of time so that the sample will not be contaiminated when the sampler is raised out of the medium in which it has been submerged.

Nov. 6, 1973 United States Patent 1 Kahl [ SUBMERSIBLE SAMPLER [76] Inventor:

Primar Examiner-S. Clement Swisher ose hKahl 8049 Pro tW ,L Y L Ca]if 92041 Spec ay a Attorney-Michael S. Striker Jan. 5, 1972 [57] ABSTRACT One or more receptacles are mounted on a frame so [22] Filed:

Appl. No.: 215,516

that they can be released therefrom. The receptacles are evacuated before use and are connected with a thin [52] US. Cl. 73/425.6

{51] Int. Cl. G0ln l/12 re ily flexi l ho e which has sealingly received in its [58] Field of Search.................... 73/425.4 R, 425.6; fr e en a glass be, an exposed end portion of which is sealed so that the vacuum in the receptacles is not broken. The tube is so looped and the glass tube so held, that when the device isactuated the glass tube [56] References Cited UNITED STATES PATENTS will be broken so as to permit aspiration of a water sam- Richard pIe into the receptacle. A time delay device closes the flexible tube after a predetermined period of time so that the sample will not be contaiminated when the sampler is raised out of the medium in which it has been submerged.

Chelminski....................::..

FOREIGN PATENTS OR APPLICATIONS mm k n MN 00365 6666 9999 I111 2234 07 934 70026 6747 3 3333 1,163,902 9/1969 Great Britain..................... 73/425.6 7 Claims, 2 Drawing Figures 1 SUBMERSIBLE SAMPLER BACKGROUND OF THE INVENTION The present invention relates generally to a submersible sampler, and more particularly to a submersible sampler which is especially effective. for obtaining uncontaminated water samples at various depths for bacteriological and other studies.

Samplers of this type are already known. As has just been suggested they are usually submerged into a body of water to a depth where it is desired to take a sample, and when the sample has been taken by the device it is brought to the surface for bacteriological and/or other studies. conventionally, devices of this type which may be submerged to significant depths from a watercraft or the like are messenger-actuated, that is the interior of their evacuated receptacle or receptacles is opened to establish communicatidn with the ambient medium for instance the surrounding body of water by a messenger which is permitted to descend from the craft overhead. Messengers in a simple form are nothing more than a weight which can freely slide under the influence of gravity along a rope or a cable connecting the suspended and submerged sampler with the craft overhead. When the messenger is released at the craft it will slide downwardly and contact a suitable portion of the sampler, tripping this portion under the influence of the impact which it exerts upon it, and thereby opening the receptacle or receptacles of the sampler to communication with the ambient medium. Detailed discussion of such messengers is not believed to be necessary because these devices are well known to those skilled in the art. However, if further information concerning the operation and exemplary construction of such messengers is desired, reference may be had to U.S. Pat. No. 3,114,334 (Joseph Kahl) for such information.

Despite the fact that as will have been understood from the above submersible samplers are already known in the art, it has been found that they are not entirely satisfactory for a variety of reasons. This includes the fact that in the known devices of this type a contamination of the sample being taken, by bacteria or other contaminants adhering to the sampler itself, cannot be completely precluded. Thus, the picture which emerges on examination ofthe sample may be misleading as to the contaminant content or type of contaminant to be found in the sample. Furthermore, the constructions according, to the, prior art have another source of contamination of the sample, in that once the receptacle of such a device is opened for aspiration of the sample, it remains open until the sampler has been recovered. This means that from thedepth at which the sampler is located when the sample is taken it must be raised through the water or other medium above this depth in order to be recovered on board the watercraft -or the like. In so doing, medium at higher levels through which the sampler passes in open condition, can enter into the sampler and become admixed with the sample which was taken at a lower level. The consequence is frequently a falsification of the sample because the composition of the medium being sampled including the type and quantities of contaminants present is often different at different depths or levels.

SUMMARY OF THE INVENTION With the various shortcomings of the prior art in mind it is a general object of the present invention to provide an apparatus of the type here under discussion which overcomes these shortcomings.

More particularly it is an object of the present invention to provide an improved submersible sampler which is not possessed of these shortcomings.

An additional object of the invention is to provide such a sampler which is relatively simple and highly reliable in its construction and operation.

Another object of the invention is to provide such a sampler which permits taking of a sample without any danger that the sample might become contaminated by contaminants which are carried by the sampler itself.

Still a further object of the invention is to provide such a sampler which, after taking of the sample, is capable of interrupting communication with the ambient medium so that as the sampler is being recovered from this medium, contamination of the sample taken by admixture with the medium at different levels than that at which the sample was taken, is avoided.

In pursuance of the above objects, and of others which will become apparent hereafter, one feature of the invention resides in a submersible sampler, particularly for taking samples of water, which briefly stated comprises a frame and at least one receptacle adapted to receive a sample and being sealed and evacuated when the sampler is put to use. The receptacle is detachably mounted on the frame by suitable mounting means and suspending means is provided for suspending the sample in a medium from which a sample is to be taken. Furthermore, I provide actuating means for establishing communication between the interior of the receptacle and the ambient medium so that a sample of this medium is aspirated into the receptacle. 1

To avoid the danger of contamination of the sample as it is being taken, i.e., contamination by contaminants which may be adhering to the sampler itself, the invention provides in a further embodiment that a flexible tube of elastomeric or similar material communicate with the receptacle or receptacles and that the flexible tube have a free end into which a tube of frangible material, for instance glass, is inserted, with the free end of the tube of frangible material in turn being sealed to avoid loss of the vacuum in the receptacle and in the tubes. The flexible tube is then looped in such a manner that it will tend to fling or move its free end provided with the frangible tube, laterally away from the sampler when released. The frangible tube, however, is held at a point near its connection with the flexible tube and it is further held by a movable triggering member in the region of its sealed end. When the triggering member is subsequently moved, for instance by the impact of a cable'guided messenger, it will then tend to bend the frangible tube which is also held in the region of its connection with the flexible tube and, because such bending is not possible, the frangible tube will break. This causes an immediate displacement of the remainder of the frangible tube which is still accommodated in the open end of the flexible tube and which latter has now been freed for movement, laterally away from the sampler under the resilient tendency of the flexible tube to straighten out the loop to which it had been formed. The movement is so rapid that by the time aspiration of sample liquid into the receptacle begins the broken end of the frangible tube is located far enough away from the sampler itself, so that no contaminants adhering to the latter will be drawn into the receptacle together with the sample being taken.

Still another embodiment of the invention provides for a delayed-action arrangement by means of which the flexible tube is closed again after a certain period of time from immersion of the sampler into the medium to be sampled, has elapsed. Of course, this period is so selected that sufficient time is available to lower the sampler to the desired depth, to send down the messenger for triggering the sampler and establishing communication with the medium, and for the medium to be aspirated. After elapse of this predetermined time the delayed-action arrangement will close the tube again by obstructing its cross-section and when the sampler is then raised through the higher levels of the medium, no further medium can enter into. the receptacle and become admixed with the sample therein.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front'perspective of a sampler in accordance with the present invention; and

FIG. 2 is a rear perspective of the sampler as shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the drawing now in detail, it will be seen that the sampler in toto is identified with reference numeral l. The device has a frame 2 which may be simply in form of a more or less plate-shaped or strip-shaped supporting member on which there is provided an anchor bracket 3. To make the anchor bracket 3 removable, for instance for replacement or for cleaning purposes, it is preferably connected with the frame 2 by means of a screw and wing-nut connection 4. The free end of that arm of the anchor bracket 3 which projects outwardly away from the frame 2 carries in the illustrated embodiment an arm or cross-bar S which may be suitably secured to this free end or which may be welded to it or be of one-piece therewith. A second cross-bar 6 extends in parallelism with the cross-bar 5, and the two are connected with one another so that they can be drawn closer together or moved farther apart, for which purpose a screw-and-wing nut connection may be provided. The opposite end portions of the arms 5 and 6 are identified with reference numeral 8 and are so contoured that each cooperating pair of end portions on the arms 5 and 6 can engage a neck or similar portion of a receptacle here illustrated as two glass bottles 10, obviously replacable with other receptacles, such as bulbs of elastomeric or other material in order to hold the receptacle or receptacles a single one could of course also be provided in place. It is preferred to provide a covering or sheet ofa padding material, for instance an elastomer, on the end portions 8; this material is identified with reference numeral 9 and of course serves to protect the necks of the receptacles 10 against damage. Farther downwardly on the frame 2, below the bracket 3, there is provided a suitable stop member l0b, for instance in form of an elastomeric or elastomerically coated member, which is located between the two receptacles 10 provided in the illustrated embodiment and serves as an abutment for them. A rubber band 10 a or analogous member is placed about the receptacles l0 and the frame 2, drawing the receptacles against the frame and towards one another into firm abutment with the member 10b so that they are reliably held on the frame 2. Of course, other means for holding them are also conceivable.

The open upper ends of the receptacles 10 are sealed, for instance by inserting a rubber stopper 1] into them. Such stoppers are each provided with an opening so that a portion of a hose or tube length 12 can be sealingly inserted into this opening in order to establish a communication between the interior of the respective receptacle 10 and the interior of the respective tube length 12. The free ends of the tube length 12 are each connected with one arm of a Y-connector l3 and the third arm of the latter is connected with one end of a main tube length 14. Certainly the tube length 14, and advantageously the length 12 also, will be made of a highly flexible, resiliently bendable material, for instance an elastomer on natural or synthetic basis.

The frame 2 also carries a further bracket 15 which is secured to it and which in the illustrated embodiment is provided in an edge portion with two inwardly extending notches l6 and 17. The bracket 15 is laterally offset from the longitudinal center line of the frame 2 and the tube length 14 is looped around so that it can first be placed into the notch 16, and subsequently in reverse direction through the notch 17. This forms two loops 30 and 29 as shown in FIG. 1. Upwardly of the notch 17 a portion 15a of the bracket 15 is provided with an additional notch 32. The free end of the tube length 14 has inserted into it a tube 33 of frangible material, for instance glass, the free end 34 of which is sealed. The tube length 14 is formed, as it emerges from the notch 17, into yet another loop 31 with a portion of the tube 33 resting in the notch 32 as illustrated. Reference numeral 36 identifies an impact member of substantial block shape which is provided in an exposed surface with the groove 35. A knob 39 is mounted on this exposed surface by means of a shaft 40 and is spring-loaded internally so that it can be drawn outwardly away from the member 36. When it is so drawn away the end portion of the tube 33 having the sealed end 34 can be inserted into the groove 35 and will be firmly retained when the knob 39 is released and under the influence of the internally located nonillustrated spring is drawn firmly against the. tube 33, urging the same into the groove 35. Member 36 is mounted on a shaft or rod 37 which, as FIG. 2 shows, is journalled in two support members 41 and 42 provided at the reverse side of the frame 2 and longitudinally spaced on the latter. The members 41 and 42 have suitable bores or passages through which the shaft 37 extends, and a biasing spring 38 surrounds the shaft 37 intermediate the member 41 and the member 36, thus urging the shaft upwardly to the end position illustrated in the drawing and which it normally assumes. If the member 36 is impacted in a sense tending to displace or shift the shaft 37 in downward direction, such downward movement will tend to bend the frangible tube 33 over the edge of the notch 32. Because the tube 33 does not bend it will break at or in the region of this edge, for which purpose a scoring line may be provided on the tube 33 with a tile or other suitable instrument. This will enhance the ease with'which the breaking will occur and at the same time, it will provide for a clean break and will afford some control as to where precisely along the length of the tube 33 the break is desired to occur. In any case, however, when such a break does occur the free end of the length of flexible tube 14, and in particular that portion forming the loop 31, is of course immediately released and will inherently tend to straighten itself out. In so doing it will fling itself towards the right in FIG. 1, to the broken-line position which is illustrated, and because this is a very rapid movement it will be completed or substantially completed by the time aspiration of sample begins through the tube 14 into the tubes 12 and from there into the receptacles 10. Because the sample is thus aspirated at a point spaced from the actual device 1 itself, contaminants which may be adhering to the device 1 cannot be aspirated together with the sample and a falsification of the sample by the presence of such contaminants which are not indigenous to the medium at the level at which the sample is being taken, is avoided.

As the device 1 must of course be suspended in the medium so that it can later be recovered, provision has been made for connecting it to a rope or cable for suspending purposes. The member 41 will be seen to have two recesses or notches 46 and 47 into which a portion of such a cable (not illustrated) can be inserted with a twisting motion; because the notches 46 and 47 are elongated substantially normal to one another the once-inserted cablecannot by itself become released. Upwardly of the member 42 the cable is clampingly connected with the device 1 by being inserted between the member 41 and a plate 43 through an opening of which a screw or bolt 44 passes on which a wing nut 45 or the like is mounted. Thus it is merely necessary to tighten the wing nut 45 until it presses the plate 43 tightly against the cable located between it and the member 41, whereby the device 41 is secured to and suspended from the cable. It will be appreciated that the connection of the cable with the member 42 via the slots 46 and 47 is not so much intended for suspending the device on the cable, as for maintaining it in proper orientation relative to the cable. The actual suspending action is obtained by means of the components 43, 44 and 45 in cooperation with the member 41.

It is possible to use two or more of these devices 1 in series. For instance, an identical device can be connected to the same suspending cable but at a still lower level, that is downwardly below the device which is illustrated in FIGS. 1 and 2. In this case, it is usually desired that the receptacles of the two devices take samples at the different levels more or less simultaneously. This requires that the device at the lower level be triggered as soon as the device at the upper level is triggered or at least shortly thereafter. To provide for this triggering of the lower device, the lower end portion of the rod 37 is formed into a substantially U-shaped hook 37a a free end 37b of which extends upwardly through a bore or passage provided for this purpose in the member 42. In the normal position of the shaft 37, that is the one illustrated in FIGS. 1 and 2,.the hook 37a will be located more or less closely adjacent the underside of the member 42. It is thus merely necessary to provide the diagrammatically illustrated messenger 50 on its suspending rope or cable 48 which is usually rather short with a loop, knot or the like 49, and to draw the rope 48 through the hook 37a after first downwardly displacing the shaft or rod 37 to provide more clearance between the hook 37aand the underside of the member 42. When the rod 37 is then released it will move upwardly to the illustrated position and the presence of the loop or knot 49 on the rope 48 will prevent the rope 48 from slipping through the hook 370. Thus the messenger 50 will be suspended beneath the illustrated device 1. If, however, the: member 36 is impacted by a messenger which descends downwardly along the cable from which the device is suspended then the hook 37a will also move downwardly away from the underside of the member 42,providing sufficient clearance for the loop or knot 49 to slip through. Now the messenger 50 will draw the loop or knot 49 through this clearance because of the weight of the messenger, and the latter which is guided in conventional manner on the length of the cable which extends from the upper device 1 to the lower device 1 will move along this length of the cable and impact the portion 36 of the lower device 1 to trigger the latter.

As already pointed out, it is desirable to provide the device 1 with a delayed-action arrangement which permits closing or termination of the communication between the interior of the receptacles 10 and the ambient medium, to prevent contamination of the sample taken when the device 1 is raised through higher levels of the medium. Such a device is illustrated in FIG. 1 and designated in toto with reference numeral 18. It has a mounting portion 19 on which a stationary portion 20 is provided, for instance by being of one-piece with the mounting portion 19. A movable portion 21 is also provided, being mounted on a rod 23 which'connects it with an additional portion 22 which is further spaced away from the stationary portion 20 than is the movable portion 21. Advantageously, the portion 22 will be provided with an upright passage in which the rod 23 is movable, with the rod 23 carrying at its upper end the movable portion 21. A biasing spring 24 surrounds the rod 23, bearing upon the portions 22 and 21 and urging the latter upwardly towards the portion 20. This is the position which the portion 21 normally tends to assume. When the portion 21 is displaced downwardly from the portion 20, however, as illustrated in FIG. 1, then there is a space 28 between them into which the loop 29 of the flexible tube section 14 is inserted. The loop 29 may actually extend laterally beyond this space 28 towards the left in FIG. 1, or it may be located as illustrated. It must not, however, extend by more than approximately one inch to the left of the space 28 because otherwise proper kinking will not be obtained and the tube will not be properly closed.

The portions 21 and 22 are in the illustrated embodiment each provided with a projection or pin 25 and I provide a delay portion or break link 26 having two longitudinally spaced holes. The length of the link 26, and the spacing between the holes thereof, is such that when the movable portion 21 has been downwardly displaced with reference to the stationary portion 20 against the action of the spring 24 to an extent providing the space 28, the pins 25 of the portions 21 and 22 can be slipped into the holes of the link 26. Of course, the pins could be provided on the link and the holes in the portions 21 and 22.

In any case, the link will be completely or in part of a material which is subject to attack by the medium in which the submersible sampler is to be submerged, and

the configuration of the link 26 is so chosen on an experimental basis that after a desired period of time the link 26 or at least the portion of the attackable material thereof will be destroyed, so that the link will part. In the illustrated embodiment the link 26 has a constricted or weakened portion 27, the minimum width of which is so calculated in conjunction with the type of material used and the thickness of the link, that after a period of time which can be readily ascertained in simple experiments or by calculation, the link will part at the weakened portion 22. When this takes place the member 21 will be moved upwardly under the influence of the spring 24, towards the stationary portion 20. in so doing, it will kink the loop 29, that is it will squeeze it together and as a result of this the crosssection of the passage in the interior of the tube 14 will be constricted to the point where it will no longer permit any flow therethrough. The device can now be raised through the medium that is be recovered for examination of the sample without any fear that the sample might become contaminated in so doing.

The break link 26 may, if the sampler is to be used in salt water, be made of magnesium which corrodes in salt water. Of course, it is possible to make only the portion 37 of magnesium, because it is essentially only this portion which should be allowed to corrode. In fact, the remainder of the link 26 except for the portion 27 can and advantageously should be covered with a suitable covering, for instance a suitable paint or the like to prevent its corrosion if the link is made in its entirety of magnesium. in use of the sampler with salt water a material other than magnesium must of course be used, because magnesium corrodes only in salt water. For instance a bar of salt or another material soluble in fresh water, could be used then in place of magnesium. Also, the configuration of the link 26 with the weakened portion 27 as illustrated could be varied and for instance the link could be of constant width with the weakened portion (the construction) 27 being omitted. The particular configuration and thickness will depend, as indicated before, upon the period of time which should lapse before the link has been destroyed by contact with the ambient medium and again will advantageously be determined experimentally, taking into account the rate of attack of the particular material by the particular medium.

The tube 14 and if desired the tubes 12 may be made of flexible synthetic or natural rubber, and it is advantageous if the entire device 1 except for the link 26 can be autoclaved. The manner in which partial vacuum may be obtained in the receptacles is known, and it will be appreciated that several approaches can be used. Rubber bulbs should advantageously be used as the receptacles 10 in preference over bottles of glass or the like, when the device 1 is to be used at greater depth, for instance over 300 feet.

It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a submersible sampler, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. A submersible sampler, particularly for taking samples of water, comprising a frame; at least one re ceptacle adapted to receive a sample and being sealed and evacuated when said sampler is put to use, said receptacle having an opening and including a flexible resiliently compressible tube forming a loop, said tube being in sealing communication with said receptacle and having a free end portion remote therefrom, and a sealed hollow frangible member projecting from said free end portion and communicating with the interior of said tube; mounting means detachably mounting said receptacle on said frame; suspending means for suspending said sampler in a medium from which a sample is to be taken; actuating means including impacting means for impacting and breaking said frangible member so as to establish communication between the interior of said receptacle and the ambient medium so that a sample of this medium is aspirated into said receptacle; and delayed action means for terminating said communication upon elapse ofa predetermined period of time following submersion of said sampler, including kinking means for engaging said loop and kinking said tube to thereby terminate said communication.

2. A sampler as defined in claim 1, further comprising holding means holding said tube so that the latter forms an additional loop intermediate said receptacle and said tubular member, the latter and an axially spaced portion of towards said tube being engaged by said actuating means and said holding means, respectively, operation of said impacting means resulting in breaking of said tubular member with simultaneous communication on the interior of said receptacle and the ambient medium on the other hand, and also causing release of said tubular member on the other hand so that said additional loop straightens out due to the inherent flexibility of said tube and displaces said tubular member away from said frame.

3. A sampler as defined in claim 1, said kinking means comprising a stationary first portion and a second portion movae toward and away from said first portion, and biasing means permanently urging said second portion toward said first portion so that said loop which is located between said portions becomes kinked by compression between them; said delayedaction means further comprising a delaying portion engaging said second portion and maintaining it spaced from said first portion and against movement toward thesame under the influence of said biasing means, for said given period of time.

4. A sampler as'defined in claim 3, said delayedaction means further including a supporting portion on which said second portion is mounted for movement toward and away from said first portion, and said second portion and supporting portion each having a projection; and wherein said delaying portion is so dimensuch attack on elapse of said period of time.

6. A sampler as defined in claim 5, wherein said medium is saltwater, and wherein at least said one section is magnesium which corrodes in :salt water.

7. A sampler as defined in claim 5, wherein said medium is a liquid, and wherein at least said one section is soluble in said liquid. 

1. A submersible sampler, particularly for taking samples of water, comprising a frame; at least one receptacle adapted to receive a sample and being sealed and evacuated when said sampler is put to use, said receptacle having an opening and including a flexible resiliently compressible tube forming a loop, said tube being in sealing communication with said receptacle and having a free end portion remote therefrom, and a sealed hollow frangible member projecting from said free end portion and communicating with the interior of said tube; mounting means detachably mounting said receptacle on said frame; suspending means for suspending said sampler in a medium from which a sample is to be taken; actuating means including impacting means for impacting and breaking said frangible member so as to establish communication between the interior of said receptacle and the ambient medium so that a sample of this medium is aspirated into said receptacle; and delayed action means for terminating said communication upon elapse of a predetermined period of time following submersion of said sampler, including kinking means for engaging said loop and kinking said tube to thereby terminate said communication.
 2. A sampler as defined in claim 1, further comprising holding means holding said tube so that the latter forms an additional loop intermediate said receptacle and said tubular member, the latter and an axially spaced portion of towards said tube being engaged by said actuating means and said holding means, respectively, opEration of said impacting means resulting in breaking of said tubular member with simultaneous communication on the interior of said receptacle and the ambient medium on the other hand, and also causing release of said tubular member on the other hand so that said additional loop straightens out due to the inherent flexibility of said tube and displaces said tubular member away from said frame.
 3. A sampler as defined in claim 1, said kinking means comprising a stationary first portion and a second portion movae toward and away from said first portion, and biasing means permanently urging said second portion toward said first portion so that said loop which is located between said portions becomes kinked by compression between them; said delayed-action means further comprising a delaying portion engaging said second portion and maintaining it spaced from said first portion and against movement toward thesame under the influence of said biasing means, for said given period of time.
 4. A sampler as defined in claim 3, said delayed-action means further including a supporting portion on which said second portion is mounted for movement toward and away from said first portion, and said second portion and supporting portion each having a projection; and wherein said delaying portion is so dimensioned as to be engageable with said projections only when said second portion is spaced from said first portion so as to maintain the former spaced from the latter for said given period of time.
 5. A sampler as defined in claim 4, wherein said delaying portion has at least one section which is of a material subject to attack by said medium during said given period of time, and to destruction resulting from such attack on elapse of said period of time.
 6. A sampler as defined in claim 5, wherein said medium is saltwater, and wherein at least said one section is magnesium which corrodes in salt water.
 7. A sampler as defined in claim 5, wherein said medium is a liquid, and wherein at least said one section is soluble in said liquid. 